Chevron U.s.a. Inc.

Dynatec, Ltd.

Sherritt International Corporation

698638 Alberta Ltd.

John Stiksma

Roman Berezowsky

Rahul Shankar Bhaduri

Ian M Masters

Michael J Collins

Derek G Kerfoot

Michael E Chalkley

Roman Michael Genik-Sas-Berezowsky

Manher M Makwana

Manher Mohan Makwana

Methods for recovering base metals, including, among other metals, molybdenum and nickel, from metal sulfides containing a Group VIB metal and a Group VIII metal. Generally, the methods comprise: contacting metal sulfides with a leaching solution containing ammonia and air to dissolve the metals into the leaching solution, forming a slurry containing soluble complexes of the metals, ammonium sulphate and solid residue containing ammonium metavanadate and any carbonaceous materials. The solid residue containing ammonium metavanadate and carbonaceous materials is then separated from the slurry and metal complexes are precipitated from the slurry by adjusting the pH. A second slurry may be formed comprising a second solid residue and a primary filtrate comprising ammonium sulfate solution that is substantially free of metals. The second solid residue is separated from the primary filtrate comprising ammonium sulfate by any means suitable for separation of solids from liquids and is then dissolved, at a second pre-selected pH, to form a Group VIB metal precipitate and a Group VIII metal containing solution. Group VIB and Group VIII metals can be easily recovered from the precipitate and solution, respectively. In some embodiments Group VB metals are recovered as well.

Recovering metals from complex metal sulfides

A method is disclosed for separating and recovering base metals from a used hydroprocessing catalyst originating from Group VIB and Group VIII metals and containing at least a Group VB metal. In one embodiment, the used catalyst is contacted with an ammonia leaching solution to dissolve and separate the Group VIB and VIII metals from the Group VB metal complex and coke associated with the used catalyst. The resulting Group VIB and VIII metal containing solution is processed through at least two additional precipitation and liquid/solid separation steps to produce, in separate processing streams, a Group VIB metal product solution (such as ammonium molybdate) and a Group VIII metal product solution (such as nickel sulfate). Additionally, two separate filtrate streams are generated from liquid-solid separation steps, which filtrate streams are combined and subjected to hydrolysis and oxidation (oxydrolysis) to generate a purified ammonium sulfate solution for further processing, such as for fertilizer.

Process for separating and recovering base metals from used hydroprocessing catalyst

A method is disclosed for separating and recovering base metals from a used hydroprocessing catalyst originating from Group VIB and Group VIII metals and containing at least a Group VB metal. In one embodiment, the method comprises the steps of: contacting the used catalyst with an ammonia leaching solution under conditions sufficient to dissolve the group VIB metal and the Group VIII metal into the leaching solution; forming a leached slurry containing at least a group VIB metal complex and at least a group VIII metal complex, ammonium sulfate and a solid residue containing at least a Group VB metal complex and coke; separating and removing from the leached slurry the solid residue and coke; precipitating from the remaining solution at least a portion of the Group VIB metal complex and at least a portion of the Group VIII metal complex by controlling the pH to form a liquid material substantially free of Group VB, Group VIB and Group VIII metals and another solid material comprising substantially Group VIB and Group VIII metal complexes. Said solid material is further processed by dissolution, means of separation, further means of precipitation and oxidative dissolution to produce, separately, a Group VIB metal product solution, a Group VIII metal product solution and a purified ammonium sulfate product solution.

A process is provided for selectively precipitating and removing manganese relative to magnesium from an acidic solution, preferably barren of one or more of cobalt, nickel, copper and zinc, but containing appreciable amounts of manganese, magnesium, and aluminum. The process comprises a) adding a first alkaline reagent, for example lime and/or limestone, to neutralize the acidic solutions and to precipitate a majority of the aluminum as aluminum-containing solids, without precipitating a substantial amount of the magnesium; b) removing the precipitated aluminum-containing solids to create an aluminum-depleted solution; c) adding a second alkaline reagent, for example lime, to the aluminum-depleted solution and aerating for a sufficient retention time to preferentially precipitate a majority of the manganese as manganese-containing solids; and d) removing the precipitated manganese-containing solids. By first precipitating and removing aluminum, the process allows for selective precipitation of manganese relative to magnesium without significant co-precipitation of magnesium, thus resulting in a savings of the total amount of the first and second alkaline reagents needed to precipitate the majority of the manganese (compared to that needed without first precipitating and removing the majority of the aluminum).

Selective precipitation of manganese from magnesium-containing solutions

There is disclosed a process for separating and recovering nickel and copper values from a nickel-copper matte which may contain iron and arsenic. Finely divided nickel-copper matte undergoes one or more steps of sulphuric acid leaching at atmospheric pressure to produce a nickel sulphate solution and an iron and/or arsenic containing copper-rich sulphide residue. The copper-rich sulphide residue is repulped in sulphuric acid solution to selectively redissolve most of the iron and arsenic and the iron and arsenic containing solution is separated from the copper-rich residue. The iron and arsenic are largely precipitated from the leach solution in a pressure hydrolysis step and the iron and arsenic containing precipitate is separated and discarded. The iron and arsenic-depleted solution is recombined with the copper-rich sulphide residue from the acid repulp step and the resulting slurry is treated in a non-oxidizing pressure leach in which nickel arsenic and iron are extracted. The process produces a nickel sulphate solution containing low levels of copper, iron and arsenic and a copper sulphide product containing low levels of nickel, iron, arsenic and other impurities.

Process for upgrading copper sulphide residues containing nickel and iron

A process for removing mercury from elemental sulphur contaminated therewith by liquid-liquid contact by mixing of the contaminated elemental sulphur in a molten state with an aqueous solution containing sulphide and polysulphide anions for extraction of the mercury contaminant from the elemental sulphur into the aqueous sulphide solution, and separating the aqueous sulphide solution containing mercury contaminant from the molten elemental sulphur to provide an elemental sulphur product substantially free from mercury.

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St. Albert, Canada

John Stiksma